1. Field of the Invention
The invention relates to an apparatus for controlling the infusion rate of an infusion means.
2. Description of the Related Art
It has been known, for making infusions, i.e., for infusing a liquid into a patient, to use hose pumps in which a hose containing the liquid is continuously squeezed in order to advance therein said liquid. Accuracy of the delivery rate depends upon the accurate speed of the hose pump, on the one hand, and upon the volume accuracy of the tube, on the other hand. Above all, volume accuracy of soft PVC hoses is particularly poor. The hose of a pump used in an infusion means is typically a disposable unit which is supplied in a sterilized condition and thrown away upon its use. In the case of such hoses, volume accuracy is dictated not only by the variation of the products, but also by ageing and wear. In the case of known hose pumps in which the hose is a disposable element producible at low cost, the maximum obtainable accuracy of the feed rate is about five percent (5%). If drugs are to be infused, such a feed accuracy is frequently inadequate.